You gat a page fault a reference to memory not owned by the running task. The task that was running was the ACHI (disk Drive) driver.
Running macOS Sierra on a 13-in MacBook Pro 2012 with an SSD device and an updated Rotating Magnetic drive attached.
Depending on the other reports you have this could de a drive problem or it could be a RAM problem. You have far too little RAM to run your Mac in an appropriately responsive way -- you need at least 6GB to run El Capitan or later, and 8GB is a little better for many users. Your machine is limited to an 8GB DIMM in each slot, for a total of 16GB.
Do you have another panic report?